Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/233

 what birds, what balls, and what other pretty things are here?

These are balls which come from the concave of the Moon.

and what is this?

This is a kind of Shell-fish, which here at Venice they call buovoli; and this also came from the Moons concave.

Indeed, it seems then, that the Moon hath a great power over these Oyster-fishes, which we call * armed sishesfishes [sic].

And this is that calculation, which I mentioned▪ of this Journey in a natural day, in an hour, in a first minute, and in a second, which a point of the Earth would make placed under the Equinoctial, and also in the parallel of 48 gr. And then followeth this, which I doubted I had committed some mistake in reciting, therefore let us read it. His positis, necesse est, terra circulariter mota, omnia ex aëre eidem, &c. Quod si hasce pilas æquales ponemus pondere, magnitudine, gravitate, & in concavo Sphæræ Lunaris positas libero descensui permittamus, si motum deorsum æquemus celeritate motui circum, (quod tamen secus est, cum pila A, &c.) elabentur minimum (ut multum cedamus adversariis) dies sex: quo tempore sexies circa terram, &c. [In English thus.] These things being supposed, it is necessary, the Earth being circularly moved, that all things from the air to the same, &c. So that if we suppose these balls to be equal in magnitude and gravity, and being placed in the concave of the Lunar Sphere, we permit them a free descent, and if we make the motion downwards equal in velocity to the motion about, (which nevertheless is otherwise, if the ball A, &c.) they shall be falling at least (that we may grant much to our adversaries) six dayes; in which time they shall be turned six times about the Earth, &c.

You have but too faithfully cited the argument of this person. From hence you may collect Simplicius, with what caution they ought to proceed, who would give themselves up to believe others in those things, which perhaps they do not believe themselves. For me thinks it a thing impossible, but that this Author was advised, that he did design to himself a circle, whose diameter (which amongst Mathematicians, is lesse than one third part of the circumference) is above 72 times bigger than it self: an errour that affirmeth that to be considerably more than 200 which is lesse than one.

It may be, that these Mathematical proportions, which are true in abstract, being once applied in concrete to Physical and Elementary circles, do not so exactly agree: And yet, I think, that the Cooper, to find the semidiameter of the bottom, which he is to fit to the Cask, doth make use of the rule of Mathematicians in abstract, although such bottomes be things meerly material,